package com.xuecheng.content.service.impl;

import com.xuecheng.content.mapper.CourseCategoryMapper;
import com.xuecheng.content.model.dto.CourseCategoryTreeDto;
import com.xuecheng.content.model.po.CourseCategory;
import com.xuecheng.content.service.CourseCategoryService;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

/**
 * @author : [lm]
 * @version : [v1.0]
 * @createTime : [2023/10/24 21:27]
 */
@Service
public class CourseCategoryServiceImpl implements CourseCategoryService {
    @Resource
    CourseCategoryMapper courseCategoryMapper;

    public List<CourseCategoryTreeDto> queryTreeNodes(String id) {
        List<CourseCategoryTreeDto> courseCategoryTreeDtos = courseCategoryMapper.selectTreeNodes(id);
        // 将list转map,以备使用,排除根节点
        Map<String, CourseCategoryTreeDto> mapTemp = courseCategoryTreeDtos.stream()
                .filter(item -> !id.equals(item.getId()))
                .collect(Collectors.toMap(CourseCategory::getId, value -> value, (key1, key2) -> key2));
        // 最终返回的list
        List<CourseCategoryTreeDto> categoryTreeDtos = new ArrayList<>();
        // 依次遍历每个元素,排除根节点
        courseCategoryTreeDtos.stream().filter(item -> !id.equals(item.getId())).forEach(item -> {
            if (item.getParentid().equals(id)) {
                categoryTreeDtos.add(item);
            }
            // 找到当前节点的父节点
            CourseCategoryTreeDto courseCategoryTreeDto = mapTemp.get(item.getParentid());
            if (courseCategoryTreeDto != null) {
                if (courseCategoryTreeDto.getChildrenTreeNodes() == null) {
                    courseCategoryTreeDto.setChildrenTreeNodes(new ArrayList<CourseCategoryTreeDto>());
                }
                // 下边开始往ChildrenTreeNodes属性中放子节点
                courseCategoryTreeDto.getChildrenTreeNodes().add(item);
            }
        });
        return categoryTreeDtos;
    }
}
